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EFFECT OF COLLISION WITH A BUOYANT RIDGE |
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| The surface contact between the Caribbean
plate and the subducted Atlantic crust is underlined by a strong
negative gravity anomaly. This feature is about 150km from the
Recent arc. Three aseismic ridges, the Barracuda, Tiburon and St.
Lucia, are located east of the Barbados complex deformation front.
The westward jump in volcanic line in the Lesser Antilles, from the Outer Arc to the Inner arc has long been an enigma in Eastern Caribbean geology. Volcanism ceased by Antigua and the Grenadines (on the Older Arc) around the mid-Oligocene (31-28Ma). Resumption of volcanism occurred (on the Recent Arc) between 22-19Ma (early Miocene) for Martinique and the Grenadines. Uplift occurred during the Eocene to mid-Miocene in the northern part of the plate. |
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